4 research outputs found
Effect of Scatterering on Coherent Anti-Stokes Raman Scattering (CARS) signals
We develop a computational framework to examine the factors responsible for
scattering-induced distortions of coherent anti-Stokes Raman scattering (CARS)
signals in turbid samples. We apply the Huygens-Fresnel Wave-based Electric
Field Superposition (HF-WEFS) method combined with the radiating dipole
approximation to compute the effects of scattering-induced distortions of focal
excitation fields on the far-field CARS signal. We analyze the effect of
spherical scatterers, placed in the vicinity of the focal volume, on the CARS
signal emitted by different objects (2{\mu}m diameter solid sphere, 2{\mu}m
diameter myelin cylinder and 2{\mu}m diameter myelin tube). We find that
distortions in the CARS signals arise not only from attenuation of the focal
field but also from scattering-induced changes in the spatial phase that
modifies the angular distribution of the CARS emission. Our simulations further
show that CARS signal attenuation can be minimized by using a high numerical
aperture condenser. Moreover, unlike the CARS intensity image, CARS images
formed by taking the ratio of CARS signals obtained using x- and y-polarized
input fields is relatively insensitive to the effects of spherical scatterers.
Our computational framework provide a mechanistic approach to characterizing
scattering-induced distortions in coherent imaging of turbid media and may
inspire bottom-up approaches for adaptive optical methods for image correction.Comment: 15 pages, 7 figure